Engine dyno vs chassis dyno

Joe DeMarzo · 01-12-2014, 09:33 PM

Does anyone know what 400HP on an engine dyno would translate into on a chassis dyno? If possible what would the reverse formula be if you had chassis dyno numbers but no engine dyno numbers?

How much HP is absorbed into the race car? Is there a percentage of what is acceptable?

Inquiring minds want to know.

Ed Wright · 01-12-2014, 10:03 PM

Joe, a loose race converter is usually close to 25%. Stock converter street cars is usually around 20%. Fluid temps have an influence on slippage, so several pulls close together often shows a drop in power as more pulls are made.
The knurl on the rollers is hard on your slicks. If you don't have street tires you could put on it, I would put 25 or 30 psi in the slicks. Use old ones if you have to. Start low as you can in high gear. Converter flash will make your torque look killer! LOL

Mike Taylor 3601 · 01-14-2014, 09:45 AM

I don't know about other brands,but Dynojet has setting where you let drums coast to stop after pull and it calculates how much the driveline is using.
Not sure how accurate that is.
Mike Taylor 3601

Ed Wright · 01-14-2014, 11:19 AM

Quote:

Originally Posted by Mike Taylor 3601

I don't know about other brands,but Dynojet has setting where you let drums coast to stop after pull and it calculates how much the driveline is using.
Not sure how accurate that is.
Mike Taylor 3601

Not very. That's what I had. :-)

Can't account for converter slippage.

01-12-2014, 09:33 PM	#1
Joe DeMarzo Senior Member Join Date: Oct 2002 Location: Mahopac, NY Posts: 666 Likes: 48 Liked 113 Times in 9 Posts	Engine dyno vs chassis dyno Does anyone know what 400HP on an engine dyno would translate into on a chassis dyno? If possible what would the reverse formula be if you had chassis dyno numbers but no engine dyno numbers? How much HP is absorbed into the race car? Is there a percentage of what is acceptable? Inquiring minds want to know. __________________ Joe DeMarzo 1317 STK

01-12-2014, 10:03 PM	#2
Ed Wright Veteran Member Join Date: Mar 2005 Location: Sand Springs, OK Posts: 8,132 Likes: 896 Liked 390 Times in 170 Posts	Re: Engine dyno vs chassis dyno Joe, a loose race converter is usually close to 25%. Stock converter street cars is usually around 20%. Fluid temps have an influence on slippage, so several pulls close together often shows a drop in power as more pulls are made. The knurl on the rollers is hard on your slicks. If you don't have street tires you could put on it, I would put 25 or 30 psi in the slicks. Use old ones if you have to. Start low as you can in high gear. Converter flash will make your torque look killer! LOL __________________ Ed Wright 4156 SS/JA

01-14-2014, 09:45 AM	#3
Mike Taylor 3601 VIP Member Join Date: Oct 2008 Location: Somerset,Ky Posts: 1,371 Likes: 352 Liked 304 Times in 102 Posts	Re: Engine dyno vs chassis dyno I don't know about other brands,but Dynojet has setting where you let drums coast to stop after pull and it calculates how much the driveline is using. Not sure how accurate that is. Mike Taylor 3601